Practical design guidelines for replacement of deficient bridges with low-water stream crossings in the rural midwest

摘要

The use of a low-water crossing may be an economically viable option to replace a structurally deficient or functionally obsolete bridge. Rural counties generally cannot afford to replace all deficient bridges and must prioritize their expenditures. In many locations the traffic volume is too low to justify the expense of bridge replacement. This situation is worsening as the rural population declines. Some counties are closing low-volume roads rather than replacing deficient bridges. In some locations a low-water stream crossing might be a practical low-cost alternative to road closure.;This thesis provides guidance to county officials and engineers on assessing the practicality of replacing a deficient bridge with a low-water crossing and selection of the best type of crossing. This report investigates several different types of low-water stream crossings and their usefulness in Kansas. A site assessment procedure is provided to rule out any type of low-water stream crossing that would be inadvisable in a particular location. A preliminary investigation and consultation with applicable permitting agencies and which type of permit to obtain for low-water stream crossing projects is outlined in this report. Guidance on designing a low-water stream crossing is included. Nine case studies of five different types of low-water crossing projects in Kansas within the last ten years are thoroughly documented accompanied by a summary of their importance. A lessons-learned section summarizes useful observations collected from county officials, regulatory personnel, and engineering consultants. To conclude the report, a summary of important information regarding LWSC projects is provided.